This application claims the benefit of Japanese Patent Application No. 2002-001738 filed Jan. 8, 2002 in the Japanese Patent Office, the disclosure of which is hereby incorporated by reference.
1. Field of the Invention
The present invention generally relates to methods of manufacturing semiconductor devices, and particularly to a method of manufacturing a semiconductor device formed with electrodes extending from the front surface to the back surface of a substrate.
2. Description of the Related Art
As an ultimate form of a semiconductor integrated circuit device, a three dimensional semiconductor integrated circuit device has been proposed.
Research has been conducted for stacking conventional two dimensional semiconductor integrated circuit devices and forming a three dimensional semiconductor integrated circuit device. In order to form the three dimensional semiconductor integrated circuit device by stacking the two dimensional semiconductor integrated circuit devices, it is necessary to connect the stacked two dimensional semiconductor integrated circuit devices at the shortest possible distance from each other. To this end, it has been found advantageous to provide a via hole that passes through the semiconductor, or a through-type via hole, in the semiconductor substrate, and connect the stacked two dimensional semiconductor integrated circuit devices to each other through such through-type via hole.
When forming the through-type via hole in the semiconductor substrate and conducting the stacking process three dimensionally, a method using reactive ion etching (RIE) that uses reactive gas, and a method of irradiating a laser beam are known as methods of forming the through-type via hole.
However, when the through-type via hole is formed using the RIE, a separate process is required to form an insulating film such as SiO2 on the surface of the through-type via hole by the CVD method and the like, after the through-type via hole is formed.
On the other hand, when the through-type via hole is formed by irradiating a laser beam, it is possible to form an insulating film such as SiO2 on the surface of the through-type via hole and to form the through-type via hole simultaneously by irradiating the laser beam in air. However, debris is generated with the formation of the through-type via hole, and a problem that such debris are attached around the through-type via hole arises. In particular, when the through-type via hole is formed by irradiating the laser beam to the silicon substrate, a problem regarding cracks caused by heat distortion of the silicon substrate arises in addition to the attachment of debris around the through-type via hole.
A method has been proposed to prevent the attachment of the debris. This method includes turning the silicon substrate upside down, irradiating such substrate with the laser beam, and the debris dropping off in a vacuum. However, another problem arises in that in a vacuum, not enough insulating film (SiO2) is formed on the surface of the through-type via hole when the through-type via hole is formed. Furthermore, a method of irradiating a laser beam to the silicon substrate immersed in water may be used to prevent cracks caused by heat distortion. However, because the debris of the silicon is porous, they may rise to the surface of the water and scatter the laser beam, thus disturbing the formation of the through-type via hole.
Accordingly, it is a general object of the present invention to provide a method of manufacturing a semiconductor device allowing an accurate and an efficient formation of the through-type via hole, preventing cracks caused by the heat distortion of the semiconductor substrate, and forming sufficient insulating film on the surface of the through-type via hole.
The present invention achieves the above object by providing a method of manufacturing a semiconductor device including the step of forming an opening in a surface of the semiconductor substrate, and the method also includes the step of irradiating a laser beam to the surface of the semiconductor substrate while running water over the surface of the substrate.
In this way, by irradiating the laser beam to the semiconductor substrate while the water is running over the surface of the semiconductor substrate, the debris generated when the through-type via hole is formed in the semiconductor substrate is removed by the flow of water, thus preventing the laser beam from scattering and making it possible to form the via hole accurately and efficiently. Furthermore, since the formation of the through-type via hole and the formation of the insulating film on the surface of the relevant via hole are carried out simultaneously, the formation of a sufficient insulating film on the surface of the through-type via hole becomes possible without providing a separate step. Furthermore, by running water over the surface of the semiconductor substrate, cracks due to heat distortion of the semiconductor substrate may be prevented.
The present invention further achieves the above object by providing a method of manufacturing a semiconductor device including steps of forming a resist film on a surface of the semiconductor substrate, and forming a resist opening for exposing the surface of the semiconductor substrate in the resist film by patterning the resist film. The step of irradiating the laser beam is performed so as to irradiate the surface of the semiconductor substrate exposed at the resist opening with the laser beam, and the step of forming the resist opening is performed so that the resist opening has a greater diameter at its upper part than at its lower part.